The flights were permitted by the United Nations Security Council, which waived an arms embargo on the conflict-ridden country to allow its armed forces to better equip themselves.
At the same time, 175 military trainers -- all but a handful of them private contractors -- arrived from Russia.
In turn, those trainers were followed by Russian companies eager to exploit the Republic's reputed mineral wealth.
The activities of those firms, which have ties to the inner circle of Russian President Vladimir Putin, were the target of three independent Russian journalists who were killed in CAR on Sunday
: Kirill Radchenko, Alexander Rastorguyev and Orkhan Dzhemal.
Their trip was backed by a foundation -- the Center for Investigation -- run by Russian exile Mikhail Khodorkovsky. A long-time foe of Putin who spent years in prison in Russia, Khodorkovsky wrote on Facebook Wednesday that the journalists were working on a project about "Russian mercenaries."
The deaths of the journalists have focused attention on Russia's growing interest in central Africa, and the relationship between the Kremlin and private Russian companies that combine security work with mining and other activities.
An ill-fated journey
The three men had traveled via Morocco on tourist visas, informing neither the Russian embassy nor CAR authorities of their presence because they wanted to investigate the activities of a Russian military contractor called PMC Wagner, the Center for Investigation said.
Perhaps not surprisingly, the journalists were refused permission to visit a site south of Bangui, where Russian trainers are based at a crumbling palace that belonged to the former ruler of CAR, Jean Bedel Bokassa. Adjacent to the palace is a long runway.
Instead, the three journalists headed north towards a gold mine at Ndassima, operated by a Russian firm and guarded by Russian contractors. But the Center for Investigation says they strayed from their planned route.
According to CAR officials, the journalists had ignored advice not to travel after dark and were ambushed some twenty miles (32 kilometres) north of the town of Sibut. They were shot dead by men wearing turbans and speaking Arabic after refusing to surrender their vehicle and equipment, the officials said. Their driver survived and raised the alarm.
Alain Nzilo, a journalist in CAR who has covered the growing Russian presence, told CNN he was surprised by the location of the ambush. The rebel presence in the area had declined in recent months, there are UN peacekeeping patrols in the area, and the military operates in Sibut.
Nzilo also found it strange that the rebels appeared to have let the driver go free. "Often, the drivers are the first to be killed and not the foreigners," he told CNN.
The Wagner effect
PMC Wagner is a secretive company -- with no known address, phone number or official records -- that recruits hundreds of former Russian soldiers, many of them special forces or "spetsnaz." In the last few years, its contractors have appeared in a growing number of conflict zones.
Wagner was sanctioned by the United States
last year for its involvement with separatists in eastern Ukraine. It has also played a major role in Syria, where dozens of its contractors were killed
or injured by US air strikes in February when they undertook an ill-fated attack on a US-supported group. Their target was one of Syria's richest oil fields in Deir Ezzor province. The company has not commented on either of the cases, or any allegations levelled against it.
More recently, Wagner appears to have developed a presence in Sudan, which shares a border with CAR. In fact, Russian instructors trained some CAR soldiers in Sudan, according to a UN report. In November last year, Sudanese President Omar al-Bashir met Vladimir Putin in Sochi
and asked him for "protection from aggressive US actions" and for Russian military experts to be sent to Sudan "to reequip [Sudan's] armed forces."
In CAR, Nzilo says the Russians combine basic humanitarian works with military training and mining. He says they are visible at three major mines and appear to be most interested in extracting diamonds and gold. Another source in CAR told CNN that the Russians sometime deploy mobile clinics for the local population at the same time as contractors and military hardware.